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b1a1176161
Introduce a new RISCVExpandPseudoInsts pass to expand atomic pseudo-instructions after register allocation. This is necessary in order to ensure that register spills aren't introduced between LL and SC, thus breaking the forward progress guarantee for the operation. AArch64 does something similar for CmpXchg (though only at O0), and Mips is moving towards this approach (see D31287). See also [this mailing list post](http://lists.llvm.org/pipermail/llvm-dev/2016-May/099490.html) from James Knight, which summarises the issues with lowering to ll/sc in IR or pre-RA. See the [accompanying RFC thread](http://lists.llvm.org/pipermail/llvm-dev/2018-June/123993.html) for an overview of the lowering strategy. Differential Revision: https://reviews.llvm.org/D47882 llvm-svn: 342534
115 lines
3.7 KiB
C++
115 lines
3.7 KiB
C++
//===-- RISCVTargetMachine.cpp - Define TargetMachine for RISCV -----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Implements the info about RISCV target spec.
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//
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//===----------------------------------------------------------------------===//
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#include "RISCV.h"
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#include "RISCVTargetMachine.h"
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#include "RISCVTargetObjectFile.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
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#include "llvm/CodeGen/TargetPassConfig.h"
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#include "llvm/IR/LegacyPassManager.h"
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#include "llvm/Support/FormattedStream.h"
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#include "llvm/Support/TargetRegistry.h"
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#include "llvm/Target/TargetOptions.h"
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using namespace llvm;
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extern "C" void LLVMInitializeRISCVTarget() {
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RegisterTargetMachine<RISCVTargetMachine> X(getTheRISCV32Target());
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RegisterTargetMachine<RISCVTargetMachine> Y(getTheRISCV64Target());
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auto PR = PassRegistry::getPassRegistry();
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initializeRISCVExpandPseudoPass(*PR);
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}
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static std::string computeDataLayout(const Triple &TT) {
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if (TT.isArch64Bit()) {
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return "e-m:e-p:64:64-i64:64-i128:128-n64-S128";
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} else {
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assert(TT.isArch32Bit() && "only RV32 and RV64 are currently supported");
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return "e-m:e-p:32:32-i64:64-n32-S128";
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}
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}
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static Reloc::Model getEffectiveRelocModel(const Triple &TT,
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Optional<Reloc::Model> RM) {
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if (!RM.hasValue())
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return Reloc::Static;
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return *RM;
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}
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static CodeModel::Model getEffectiveCodeModel(Optional<CodeModel::Model> CM) {
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if (CM)
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return *CM;
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return CodeModel::Small;
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}
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RISCVTargetMachine::RISCVTargetMachine(const Target &T, const Triple &TT,
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StringRef CPU, StringRef FS,
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const TargetOptions &Options,
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Optional<Reloc::Model> RM,
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Optional<CodeModel::Model> CM,
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CodeGenOpt::Level OL, bool JIT)
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: LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS, Options,
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getEffectiveRelocModel(TT, RM),
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getEffectiveCodeModel(CM), OL),
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TLOF(make_unique<RISCVELFTargetObjectFile>()),
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Subtarget(TT, CPU, FS, *this) {
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initAsmInfo();
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}
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namespace {
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class RISCVPassConfig : public TargetPassConfig {
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public:
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RISCVPassConfig(RISCVTargetMachine &TM, PassManagerBase &PM)
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: TargetPassConfig(TM, PM) {}
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RISCVTargetMachine &getRISCVTargetMachine() const {
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return getTM<RISCVTargetMachine>();
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}
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void addIRPasses() override;
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bool addInstSelector() override;
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void addPreEmitPass() override;
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void addPreEmitPass2() override;
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void addPreRegAlloc() override;
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};
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}
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TargetPassConfig *RISCVTargetMachine::createPassConfig(PassManagerBase &PM) {
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return new RISCVPassConfig(*this, PM);
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}
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void RISCVPassConfig::addIRPasses() {
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addPass(createAtomicExpandPass());
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TargetPassConfig::addIRPasses();
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}
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bool RISCVPassConfig::addInstSelector() {
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addPass(createRISCVISelDag(getRISCVTargetMachine()));
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return false;
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}
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void RISCVPassConfig::addPreEmitPass() { addPass(&BranchRelaxationPassID); }
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void RISCVPassConfig::addPreEmitPass2() {
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// Schedule the expansion of AMOs at the last possible moment, avoiding the
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// possibility for other passes to break the requirements for forward
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// progress in the LR/SC block.
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addPass(createRISCVExpandPseudoPass());
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}
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void RISCVPassConfig::addPreRegAlloc() {
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addPass(createRISCVMergeBaseOffsetOptPass());
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}
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